1. Field of the Invention
The present invention relates generally to man hole covers and, more specifically, to an improved temporary manhole insert for securing a manhole passageway having a generally cylindrical structure with an inflatable, ring like structure encompassing the outer rim of the removable plate portion of the insert.
The insert with the inflatable rim is placed within the manhole aperture and then inflated to expand until the insert is secured in position. Once positioned therein, passage is provided through the removal of a pliable center plate. The manhole insert of the present invention prevents debris such as rocks, dust, asphalt and other debris from falling into the manhole during adjustments to the casting for asphalt overlay.
2. Description of the Prior Art
There are other cover devices designed for manholes. Typical of these is U.S. Pat. No. 1,940,924 issued to Taylor on Dec. 26, 1933.
Another patent was issued to Pelsue on Dec. 27, 1966 as U.S. Pat. No. 3,294,000. Yet another U.S. Pat. No. 5,052,851 was issued to Frishauf on Oct. 1, 1991 and still yet another was issued on Dec. 28, 1999 to Bowman as U.S. Pat. No. 6,007,270.
Another patent was issued to Brockway, et al. on Nov. 28, 2000 as U.S. Pat. No. 6,152,455. Yet another U.S. Pat. No. 6,682,257 was issued to Zappe on Jan. 27, 2004. Another was issued to Zappe on May 3, 2005 as U.S. Pat. No. 6,887,012 and still yet another was issued on Oct. 11, 2005 to Brockway as U.S. Pat. No. 6,953,194.
Another patent was issued to Pelsue on Jun. 15, 1966 as U.K. Patent No. GB1032839. Yet another U.K. Patent No. GB2285473 was issued to Mitchell, et al. on Jul. 12, 1995. Another was issued to Tamio on Feb. 22, 2000 as Japanese Patent No. Feb. 22, 2000 and still yet another was issued on Jul. 23, 2003 to Gudrun, et al. as European Patent Application EP1329558.